In the field of fluid conveyance, particularly piping fit with valves, fluids containing particulate matter can result in accumulations or sand-packing that eventually interferes with valve operation. For example, in the industry of oil well completion, stimulation, operation and servicing, particulates introduced to the wellbore or solids flowing from the wellbore can infiltrate, build up, or otherwise interfere with the operation of the valve stem, the gate, and other moving components required for valve operation.
In the practice of fracturing or otherwise stimulating a subterranean formation, accessed by a wellbore, fluid-solid mixtures of fracturing fluids and large amounts of abrasive are often pumped down the wellbore to the wellbore formation by high pressure pumps. The wellhead and related structure are fit with isolation valves. Abrasives in the fracturing fluids include particulate matter such as proppants, often provided in the form of resin and sand. Herein, the particulates are referred to generically as sand for simplicity. A frachead directs the fracturing fluid and sand therein through a wellhead and down the wellbore. The fracturing block or frachead is attached to the wellhead or other tubular structures or fixtures located on the wellhead. Fluid lines from high pressure pumps are attached to the frachead and are capable of withstanding high pressures and are resistant to erosion from the abrasive sand.
A multitude of other surface equipment, such a remote ball launchers and ball catchers, can be operationally attached to the frachead. In order to increase operational safety and to provide finer operational control, each piece of surface equipment operational attached to the frachead can be isolated from one another by installing isolation valves therebetween. Further, the frachead itself can be isolated from the source of the fracturing fluids through isolation valves. Common isolation valves that can be used are gate valves.
As fracturing fluid is pumped at high pressures through the various surface wellhead equipment, the sand carried by the fracturing fluid can enter into various cavities in the valves and collect, stick, settle or otherwise remain trapped therein, resulting in sand packing.
Sand packing in the isolation valves can impede or prevent the isolation valve from properly, and fully, opening and closing. Improper closing of the isolation valves creates safety issues as the various pieces of equipment can remain in fluid communication at high pressures and prevent full isolation thereof, while improper opening of the isolation valves results in restriction of the bore diameter which can impact fluid pressures, rates therethrough and encourage erosion. In instances where a wellbore isolation valve is restricted, the restriction can also prevent larger diameter tools, such as balls or other downhole tools, from passing therethrough and blocking access to the downhole operations.
To remove sand packing in isolation valves, or replace compromised valves, fracturing operations have to be temporarily suspended or shut down which can lead to costly, non-productive downtime and potential operational difficulties including falling out and downhole deposition of otherwise flow-suspended sand, resulting in costly wellbore blockages.